Benzimidazole perylene particles are a known extrinsic charge generating material that can be employed in a charge generating layer of a photoreceptor. Photogenerated charge carriers need to be brought out of the surface of the benzimidazole perylene particles before the charge carriers recombine and move into the charge transport layer under the applied electric field. The process is slowed down in certain types of binder resin employed in the charge generating layer, especially at low electric field. Therefore, the photoinduced discharge curve ("PIDC") gets softer at low electric field. Soft PIDC means that as the exposure light energy is increased, the amount of surface voltage change due to the exposure of the photoreceptor to light is proportionally less. Such a soft PIDC will require a more powerful light source for imaging. Thus, there is a need, which the present invention addresses, for a more sensitive photoreceptor. A photoreceptor with enhanced sensitivity will reduce the need to employ a more powerful light source, thereby reducing cost.
Conventional photoreceptors and their materials are disclosed in Katayama et al., U.S. Pat. No. 5,489,496; Yashiki, U.S. Pat. No. 4,579,801; Yashiki, U.S. Pat. No. 4,518,669; Seki et al., U.S. Pat. No. 4,775,605; Kawahara, U.S. Pat. No. 5,656,407; Markovics et al., U.S. Pat. No. 5,641,599; Monbaliu et al., U.S. Pat. No. 5,344,734; Terrell et al., U.S. Pat. No. 5,721,080; and Yoshihara, U.S. Pat. No. 5,017,449.
Conventional charge blocking layers are also disclosed in U.S. Pat. No. 4,464,450; U.S. Pat. No. 5,449,573; U.S. Pat. No. 5,385,796; and Obinata et al, U.S. Pat. No. 5,928,824.